DDD & Event sourcing workshop

What we will try to implement

• an event-sourced aggregate: Person
• some value objects for a Person: Name, EmailAddress, Address
• some domain events: PersonRegistered, PersonEmailAddressConfirmed, PersonAddressAdded, PersonAddressChanged
• the methods in the Person aggregate which will cause the above events
• we'll try to work test-driven as much as possible

Let's apply

• DDD principles and
• make the model Event sourced

My choice of programming language

• Golang

Steps

First Part

• Create Name value object and tests (I will not mention tests in the following steps, just create them always ;)
• Create simple Email value object, only with the "email" value (confirm will come later)
• Create Address value object with basic fields (CountryCode, PostalCode,City,Street,HouseNumber)
• Create Person entity (aggregate root) with basic method Register
• Create domain event PersonRegistered
• Follow with methods RecordedEvents, recordThat and apply
• Add new behaviour to the Email - "confirm email"
  • adapt value object and also the aggregate
  • create domain event EmailConfirmed
• Implement Address events
  • AddressAdded
  • AddressChanged

Next Part [TODO]

• Implement the event store (maybe with PostgreSQL)

Questions

• Why do we have "add home address" and "change home address" - why do we have two distinct actions in our domain?

Notes / findings

• Visibilities in Golang are not that powerful as in other languages